change your binding to be {_cartItem.toy.getDescription()} directly (which
is implied to work from your definition of Toy, but not the same as your
original binding).
Then change getDescription() to define a specific bindable event:
[Bindable("getDescriptionChanged")]
public function getDescription():String { ... }
And then you need to broadcast the event "getDescriptionChanged" anywhere
that results in a change in value (i.e., never in the Toy base class, but in
the "color" setter for ToyTruck).
HTH,
Sam
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-----Original Message-----
From: [email protected] [mailto:[EMAIL PROTECTED] On
Behalf Of Brian
Sent: Monday, December 10, 2007 11:01 AM
To: [email protected]
Subject: [flexcoders] help with 'deep' data binding
I'm reposting this from late Friday afternoon, hope that's OK. I found
a thread where something similar, and having to do with Cairngorm, was
described as 'deep' data binding. I'd appreciate any help
--- In [email protected], "Brian" <[EMAIL PROTECTED]> wrote:
>
> I'm trying to bind a Text control to a function to get the description
> of an item, when a property of a class inside that item changes. Is
> this at all possible? I've tried different variations of binding
> functions, Binding tags, etc. and still can't get it to work. Here are
> code snippets that will hopefully explain what I'm trying to do.
>
> package src
> {
> [Bindable]
> public class Toy
> {
> public getDescription():String {
> // will be overridden in subclasses
> return "";
> }
> }
> }
>
> package src
> {
> [Bindable]
> public class ToyTruck extends Toy
> {
> public var color:String;
>
> public override function getDescription():String {
> return color + " truck";
> }
> }
> }
>
> package cart
> {
> import src.*;
> [Bindable]
> public class CartItem
> {
> public var quantity:int
> public var toy:Toy;
>
> public function getDescription():String {
> return quantity + " " + toy.getDescription();
> }
> }
> }
>
> MXML component
> <mx:VBox>
> <mx:Script>
> <![CDATA[
> import cart.CartItem;
> import src.*;
>
> [Bindable]
> public var _cartItem;
>
> public function getText(toy:Toy):String {
> return _packItem.getDescription();
> }
> ]]>
> </mx:Script>
> <mx:Text id="itemDesc" text="{getText(_cartItem.toy)}"/>
> </mx:Vbox>
>
> What I'd like to have happen is have the Text control update when the
> ToyTruck.color is changed by other events. Is this possible? The above
> code snippets is what I'm currently trying but the Tex is not
> updating. Even though the toy is not used directly in the getText()
> function, I thought having it as a parameter was how the function was
> triggered. The docs say that when a bindable property as an argument
> of the function changes, the function executes.
>
> In reality, there are different properties for different subclasses of
> Toy, which could be modified by several different events. This is why
> I'm trying to get the binding to work, so I don't have to manually
> update the Text control all over the place. I thought that was the
> whole point of Binding, but maybe I'm missing something.
>
> Or do I have to use a Binding tab for each of those different
> properties of the subclasses? I haven't tried that yet but I don't
> think that would work because the source has to be a string, right?
>
> Thanks
>
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